1. Field of the Invention
This invention pertains generally to the field of inflatable mattresses and more particularly is directed to an air support bed of modular construction featuring a removable air support unit in a bed structure. Air support units having different body support characteristics can be readily exchanged to adapt a particular bed to changing requirements.
2. State of the Prior Art
Air support beds are in widespread use in medical care settings, particularly for patients requiring long term bed care. Bed ridden patients are susceptible to skin ulcerations caused by excessive buildup of heat and moisture on the skin, typically in combination with pressure, friction and shear forces exerted on the skin by contact with the bed surface, which tend to close off capillary blood circulation in skin tissues. Such ulcerations are painful and slow to heal, and are a frequent complication in bed ridden individuals. Air mattresses and air support beds have been found to alleviate this problem because the air filled chambers of the bed tend to conform to the anatomy of the bed ridden patient better than ordinary mattresses and consequently distribute pressure over a wider area of skin, thereby diminishing the risk and severity of skin ulcerations. Furthermore, the firmness of an air mattress can be controlled and adjusted simply by increasing or diminishing the internal air pressure, and air support beds featuring positive pressure regulation by means of electronically controlled air pumps have been developed. Air mattresses with compartmentalized air chambers which can be individually pressurized to different degrees are used for creating different zones of varying firmness adapted to the requirements of different anatomical areas of the patient's anatomy.
The requirements of long term medical bed care has led to the development of four principal classes of air beds.
Static pressure air beds are kept inflated to a preset pressure by an air blower or air pump.
Computerized or positive pressure control air beds feature one or more air pressure sensors connected to an electronic control system which actuates an air pump and an air relief valve, supplying or venting compressed air as needed to hold the internal pressure of the air chambers of the bed at a preset level, compensating as the user shift positions or gets in and out of the bed.
Cyclic pressure air beds alternately inflate and deflate different air chambers of the bed mattress so as to periodically shift pressure between different areas of the user's anatomy. The cyclic action of the air bed tends to stimulate the affected tissues and provides an opportunity for blood circulation to re-establish itself in those areas.
Low loss air beds have air chambers with finely perforated walls which allow pressurized air to leak continuously from the air chambers at a controlled rate into the bed cavity containing the air support unit. The continuous airflow under the patient carries away excess moisture and prevents heat buildup, which as earlier mentioned are among the principal causes of skin tissue breakdown in bed ridden patients.
Each of these categories of air beds has its particular advantages, and one type may be preferred over the others depending on a combination of medical benefit and economic considerations. There are substantial cost differences between beds in the different categories, so that the more elaborate units may be reserved for those patients in greatest need of this type of support.
Existing medical air support beds are constructed to provide a specific type of support. Consequently, an inventory of the different types of air beds must be kept on hand in order to anticipate the needs of the patient population of a medical institution. If the existing inventory is inadequate to meet the needs of the moment the result may be an inability to provide optimum bed support for some patients. Since patient loads and requirements fluctuate constantly medical institutions may need to keep a large and costly inventory of different types of air beds.
What is needed is an air bed which can be readily adapted to provide different types of support as may be required by particular patients without need for replacement of the entire bed. The conversion should be relatively quick and simple with only minimal training of available personnel. Furthermore, the ability to exchange support characteristics of the air bed should not greatly add to the cost or complexity of the bed.